DUAL 5W, DIGITAL DIMMING CCFL INVERTER MODULE
A MICROSEMI COMPANY
PRELIMINARY DATA SHEET
LAMP VOLTAGE & LAMP CURRENT – BURST MODE OPERATION
!" – 50% Burst Duty Cycle
!" # – 5% Burst Duty Cycle
Rather than using the traditional dimming technique of
varying lamp current magnitude to adjust light output,
RangeMAX inverters use a fixed lamp current value with a duty
cycle control method.
The lamp current burst width can be modulated from 100%
(continuous lamp current) down to a 5% duty cycle, allowing the
lamp to be dimmed to less than 3% of its full brightness.
As can be seen in Trace 4 of Figure 3 photo at right, careful
design consideration was given to controlling lamp start voltage
to softly start current flow. This eliminates current overshoot
that can result in premature cathode wear and reduce lamp life.
!" $ – 5% Burst Duty Cycle (Expanded Time Base)
V SYN C
• Integrated brightness control circuit includes a DC
voltage to pulse width converter that minimizes system
design work and system noise susceptibility. This
provides a familiar and convenient interface while
reducing the potential for externally induced noise,
which can cause lamp flicker.
• RangeMAX inverter modules are designed to operate
with the burst frequency synchronized to the video frame
rate. This provides operation with no visible display
disturbances caused by beat frequencies between the
lamps and video frame rates. In this synchronous mode,
the inverter burst rate operates at twice the video refresh
rate, well beyond standard 50/60Hz video refresh rates
where the eye can perceive pulsing light.
– RangeMAX Simplified Block Diagram
Copyright © 2000
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570